Mineral Resources On-Line Spatial Data
Mineral Resources > Online Spatial Data > Geology > by state > Tennessee Geology
Geologic units in McNairy county, Tennessee
- Midway Group including Porters Creek Clay and Clayton Formation (Tertiary) at surface, covers 2 % of this area
Midway Group - includes Porters Creek Clay - Pale-brown to brownish-gray, massive, blocky clay; locally contains glauconitic sand. Thickness 130 to 170 feet. Also includes Clayton Formation- Glauconitic sand, argillaceous and locally fossiliferous; at base in Hardeman County is an impure fossiliferous limestone. Thickness 30 to 70 feet.
- High-level alluvial deposits (Quaternary-Tertiary) at surface, covers 5 % of this area
High-level Alluvial Deposits - Iron-stained gravel, sand, silt, and clay; variable in thickness but generally less then 60 feet thick.
- Alluvial deposits (Quaternary) at surface, covers 17 % of this area
Alluvial Deposits - Sand, silt, clay, and gravel. In flood plain of Mississippi River more than 100 feet thick; in smaller streams generally less than 20 feet thick.
- Owl Creek Formation (Cretaceous) at surface, covers 1 % of this area
Owl Creek Formation - Sandy clay, greenish gray, glauconitic, fossiliferous; merges northward into unfossiliferous clays and sands. Thickness 0 to about 40 feet.
- Claiborne and Wilcox Formation (Tertiary) at surface, covers < 0.1 % of this area
Claiborne and Wilcox Formations -- Irregularly bedded sand, locally interbedded with lenses and beds of gray to white clay, silty clay, lignitic clay, and lignite. Thickness more than 400 feet.
- Sardis Formation (Cretaceous) at surface, covers < 0.1 % of this area
Sardis Formation - Quartz sand and glauconite sand, argillaceous and locally fossiliferous. (Mapped with Kcc north of Beech River.) Maximum thickness 70 feet.
- Coffee Sand (Cretaceous) at surface, covers 3 % of this area
Coffee Sand - Loose fine-grained sand, light-gray, sparsely glauconitic, locally interbedded with laminated lignitic clay. Thickness 25 to 200 feet; thins northward.
- Coon Creek Formation (Cretaceous) at surface, covers 19 % of this area
Coon Creek Formation - Fossiliferous, micaceous sand, silty and glauconitic; locally fossiliferous sandy clay at base. Siderite concretions common in upper part. Thickness about 140 feet.
- McNairy Sand (Cretaceous) at surface, covers 42 % of this area
McNairy Sand - Predominantly sand, in places interbedded with silty light-gray clays. Fine-grained sand at base, locally contains heavy minerals. Thickness about 300 feet.
- Demopolis Formation (Cretaceous) at surface, covers 10 % of this area
Demopolis Formation - Marl and calcareous clay, light-gray, fossiliferous, locally glauconitic and sandy. Merges northward into sands mapped as Kcc. Maximum thickness 180 feet.